Should I add a buffer tank to my UFH circuit?

[MarkyP]

We have two wet system UFH zones in kitchen/sitting room side extension.  They are heated via our main oil boiler currently. The UFH system is Uponor and seems standard with a manifold mixer to regulate flow and supply water temp, mixing hot water from boiler with return water from UFH to provide a feed into water at around 38 degrees. The boiler also heats hot water in a pressurised cylinder and also conventional rads to rest of the house.  

 

I used a plumbing firm for the UFH but have since read on here that it is a good idea to use a buffer tank to stop the boiler short cycling ( which it does when running only the ufh). 

 

Should I retro fit a buffer cylinder? Is there any rule of thumb on sizing it? I have some space in a downstairs cupboard near the manifold but not much.

 

 

[BotusBuild]

Adding a buffer tank will help you as it sounds like there is a small volume of liquid in the UFH pipework (assuming here that the pipe runs are probably between 75-150m for what you describe). Depending on the space available, a 100 litre buffer tank should be OK. Make sure that the boiler then has a thermostatic feedback from the buffer to tell it when to switch off ?

[PeterW]

A cheap copper cylinder will work fine - direct one with an immersion may help too for redundancy. 

 

Simple pipework but a buffer cannot go over 1.5 bar in reality so watch your system pressures or you will pop the bottom on a copper cylinder.